package com.personal.test.common.java8;

/**
 * @author linyh
 * @version 1.0
 * @email 1503386669@qq.com
 * @date 2020/11/4 11:19
 */

/**
 * 测试Lambda表达式
 */
public class Java8TesterOfLambda {
    public static void main(String args[]){
        Java8TesterOfLambda tester = new Java8TesterOfLambda();
        // 类型声明
        MathOperation addition = (int a, int b) -> a + b;
        // 不用类型声明
        MathOperation subtraction = (a, b) -> a - b;
        // 大括号中的返回语句
        MathOperation multiplication = (int a, int b) -> { return a * b; };
        // 没有大括号及返回语句
        MathOperation division = (int a, int b) -> a / b;
        System.out.println("10 + 5 = " + tester.operate(10, 5, addition));
        System.out.println("10 - 5 = " + tester.operate(10, 5, subtraction));
        System.out.println("10 x 5 = " + tester.operate(10, 5, multiplication));
        System.out.println("10 / 5 = " + tester.operate(10, 5, division));
        // 不用括号
        GreetingService greetService1 = message ->
                System.out.println("Hello " + message);
        // 用括号
        GreetingService greetService2 = (message) ->
                System.out.println("Hello " + message);
        greetService1.sayMessage("Runoob");
        greetService2.sayMessage("Google");
    }

    /**
     * 函数式接口
     * 只能包含一个方法声明
     */
    @FunctionalInterface
    interface MathOperation {
        int operation(int a, int b);
    }

    /**
     * 函数式接口
     * 只能包含一个方法声明
     */
    @FunctionalInterface
    interface GreetingService {
        void sayMessage(String message);
    }

    /**
     * Java8TesterOfLambda内部私有方法
     * @param a
     * @param b
     * @param mathOperation
     * @return
     */
    private int operate(int a, int b, MathOperation mathOperation){
        return mathOperation.operation(a, b);
    }
}
